Self Returning Contamination Barrier

ABSTRACT

A barrier of a vacuum pump prevents contamination from entering a vacuum pump air line. The barrier separates parts of the pump and is moveable between an initial state and a distended state. The barrier is assembled within the pump with a pre-load. When the vacuum source is applied to the barrier, the barrier achieves a distended state and when the vacuum source is released, the barrier incrementally self returns to an initial state. The geometry and material construction of the barrier, along with the pre-load, assists in returning the barrier on its own to the initial state from the distended state.

CROSS-REFERENCE TO RELATED APPLICATIONS

This application is a continuation of U.S. patent application Ser. No.11/591,276, entitled “Self Returning Contamination Barrier,” filed Nov.1, 2006, the contents of which are fully incorporated herein byreference.

FIELD OF THE INVENTION

The present invention relates generally to contamination barriers forpumps, and more particularly in one aspect to a breastpump assemblyincluding an improved barrier to prevent milk from entering and possiblycontaminating a pumping mechanism for the breastpump.

BACKGROUND OF THE INVENTION

Breastpumps are well known, and generally comprise a hood or shield thatfits over the breast, a vacuum pump connected to the hood for generatingan intermittent vacuum (or negative pressure) within the breastshield,and a receptacle for expressed milk. Negative pressure is pressure belowatmospheric pressure. The intermittent suction action of the vacuum pumpserves to pull on the breast and nipple and thereby express milk. Theexpressed milk typically flows from the hood, through a conduitstructure and into a collection container, such as a baby bottle, forstorage and later use.

Breastpumps can be manually or electrically operated. With manuallyoperated pumps, the pumping action is done by reciprocating a piston orlever by hand, or compressing a flexible bulb, as shown in Medela's U.S.Publication No. 2004/0039330. With electrically operated pumps, thepumping action generated by a motor driven pump and typically conveyedby an air hose, or air line, that connects to the breastshield assembly.

In most instances, the pressure applied at the breast is a negativepressure (suction). That negative pressure is typically applied to theinterior of the breastshield in a singular fashion, that is, without anykind of differential vacuum application over the breastshield as awhole. This has ordinarily been done through a cyclic pattern, e.g.,intermittent suction. Breastpumps of this kind, which only pull andrelease suction, are known as simple pumps.

There are also breastpumps that apply a vacuum pressure and a positivepressure, typically applied to the interior of the breastshield, knownas complex pumps. Typically, a vacuum pump that generates a positivepressure, (pressure above atmospheric pressure,) assists in forcing theexpressed milk through a valve and into the collection container. Abreastpump of the foregoing type is shown in U.S. Pat. No. 4,857,051 toLarsson, the disclosure of which is incorporated herein by reference forfurther details of a breastpump assembly in general.

Positive pressure opens the valve, often used with breastpumps, toassist in movement of the breast milk through the conduit structure andinto the bottle. During pumping, the expelled milk will ultimately beseparated from the air drawn back and forth in the air hose, and to andfrom the breastshield. Some breastpumps use gravity and geometry, suchas a splashguard, to separate the milk and air (air being the workingfluid), but these breastpumps are often difficult to clean, and theorientation of the breastshield in use may be thereby limited. Otherbreastpumps use a filter, for example a hydrophobic filter, to preventmilk from entering the air hose and/or pump. That filter can becomesaturated, shutting down pumping; it must also be cleaned and evenperiodically replaced. The objective of these efforts is to isolateparts of the breastpump from milk or other liquids/bacteriologicalmaterial that would constitute a contaminant, or foul the works (such asmilk finding its way to the pump mechanism). In institutional settings,for another example, it is desirable to have a pump that can betransferred between mothers, yet the pump mechanism remains isolatedfrom one mother to the next.

Some conventional electric breastpumps also use a moveable, sometimescollapsible, membrane or barrier, that separates the breastshield(including valve) from the pumping mechanism. During operation, twopressures are realized: a first pressure on the vacuum side of themembrane, or pump vacuum, and a second pressure on the breastshield sideof the membrane, or breastshield vacuum. The vacuum pump communicates anegative pressure to the membrane via the air hose, such that the firstpressure is greater than the second pressure, or in similar terms, thepump vacuum is greater than the breastshield vacuum. This differentialvacuum causes the membrane to collapse or move. A problem with someconventional breastpumps of this type is that the membrane may notreturn to an initial state or position, i.e., it may end up locking orbuckling.

This type of breastpump generally requires a positive pressure from thebreastshield side of the membrane to push the membrane past a lock orbuckle point in order to return the membrane to the non-collapsed stateduring a breastpump cycle. A breastpump of the foregoing type is shownin U.S. Pat. No. 5,941,847 to Huber. A typical issue with these types ofpumps is that leakages, evaporation, expulsion of milk and breastextension hysteresis do not ensure that the membrane returns fully toits initial non-collapsed state without the assistance of a positivepressure.

Some conventional manual breastpumps also include a collapsible ormovable membrane that has a significant energy loss in “transferring”vacuum from one side to the other. The mechanical coefficient across thebarrier membrane needs dramatic improvement.

Accordingly, a breastpump that reduces or eliminates contamination inthe upstream pump air line and pump by isolating the pressure sourcefrom the expressed milk is desired to protect the user and preventdamage to the pump mechanism. A much more energy efficient pump systemthat uses a movable membrane/barrier for vacuum communication is alsohighly desirable.

SUMMARY OF THE INVENTION

The present invention, in perhaps one of its broadest expressions,comprises a barrier for a pump or a pumping system, that separates partsof the pump while transferring a pressure change across the barrier.When a pressure, as from a vacuum source, is applied to the barrier, thebarrier achieves a distended state and when the vacuum is released, asby a return to atmospheric pressure, the barrier has a natural bias thatreturns it to an initial “pre-loaded” state. This advantageously canactually yield a slight positive pressure from the system and thebreastshield side or the downstream side of the barrier (relative to theupstream vacuum source). “Bias” is used herein to describe the pre-settendency of the barrier to try and return to this initial state.

Although embodiments of the present invention discussed herein aredirected to breastpump systems, it is contemplated that various otherapplications for a self-returning barrier exist, for example, in ageneral sense to similar pump systems. This applies to other attributesof the invention as well.

Another object of the present invention is to provide a self-returningbarrier such that a source of positive pressure from the pump is notrequired to return the barrier to its initial state from a distendedstate during a breastpump cycle, and further that the mechanicaltransfer of vacuum across the barrier is highly efficient. The forcerequired to distend the barrier of the present invention is determinedby material construction, breastshield size, breast size, and the vacuumlevel of the pump; but in any of these systems, displacement of thebarrier to a distended state requires that the pump vacuum is greaterthan the breastshield vacuum, i.e., there is energy lost in themechanical transfer of vacuum from one side of the barrier to the other.The present invention achieves a highly efficient mechanical transfer.

The geometry of the inventive barrier acts as a spring in a preferredform. The barrier geometry maintains a low spring rate. A sufficientspring force designed into the barrier returns the barrier to theinitial state, and further can assist in the expulsion of milk through avalve and into a collection container.

Another object of the present invention is to provide a barrier with apre-loaded residual force when assembled. That is, the barrier iscompressed along a central axis in the assembled state. The barrier isthus pre-loaded, i.e., biased when in this assembled state.

Yet another object is to provide a self-returning barrier that returnsto an initial state from a distended state in a brief time frame, i.e.,150 milliseconds or less, without assistance from the pump to therebyfurther, minimize energy expenditure on the breastpump system.

Another object of the present invention is to provide a barrier toisolate parts of the pump, as from contaminants or the like that couldotherwise pass.

Yet another aspect of the present invention is to provide aself-returning barrier that collapses uniformly as well as returns to aninitial state uniformly. The barrier of the present invention therebyeliminates the need to apply force to move through non-uniform states,such as in a lock or buckle condition of the prior art. The barrier ofthe present invention includes a corrugated geometry to prevent it fromlocking up or buckling. In one form this geometry comprises one or moreundulations in the barrier that are generally concentric on a convexsurface.

During collapse or achievement of a distended state, the barrier of thepresent invention in a preferred form never locks or buckles, evenduring circumstances when the pump vacuum remains less than thebreastshield vacuum or when the pump vacuum is equal to the breastshieldvacuum. Likewise, the barrier of the present invention never locks orbuckles during return from a distended state to an initial state, evenduring the circumstances when the vacuum pressure is greater than thebreastshield vacuum or the vacuums are equal.

Another aspect of the present invention is to provide a self-returningbarrier that works with manually operated as well as electricallyoperated breastpumps. Furthermore, a self-returning barrier is providedthat may function with complex electrical pumps providing a negativepressure and a positive pressure, and also with a simple pump providingonly negative pressure (and a vent to atmosphere).

In particular, the barrier of the present invention does not requireassistance from the vacuum pump, such as the positive force of air, forthe barrier to return to its initial state during a breastpump cycle.The geometric and material construction of the barrier itself returnsthe barrier to its initial state after a suction phase.

In a broad embodiment, the present invention is a movable barrier forseparating parts of a pump, as to prevent contamination that includes aninitial state wherein the barrier is assembled as to possess a pre-load.When a vacuum source is applied to the barrier, the barrier achieves adistended state, and when the vacuum source is released, the barrierincrementally self-returns to an initial state.

The present invention, with application to a breastpump assembly, has abreastshield, a conduit structure and a collection container (bottle). Aresilient barrier is assembled in a pre-loaded condition in a housing,which is located in an air pressure line, typically a vacuum line. Whena vacuum is applied, the barrier achieves a distended state, and whenthe vacuum is released, the barrier utilizes the pre-load as a springaction to assist in transforming to its initial pre-load state.

In another aspect, a breastpump assembly has a contamination barrierlocated in a vacuum line between a vacuum pump and a breastshield. Ahousing has a breastshield side and a vacuum side, also referred toherein as vacuum pump side, separated and isolated from one another bythe barrier. The barrier is assembled within the housing in an initialpre-loaded state such that said barrier has a bias toward thebreastshield side when no vacuum is applied. When vacuum is applied, thebarrier achieves a distended state, and when the vacuum is released, thebarrier returns to the initial state.

In one embodiment, the barrier has a generally convex shape at least inpart as presented by a convex barrier side, and is assembled within theforegoing housing so that the bias presses the convex barrier sideagainst an internal breastshield side sidewall of the housing in theinitial state. The convex barrier side has at least one undulationformed in its surface generally concentric with the center of theconvexity of the barrier.

In a most preferred form, the internal breastshield side sidewall has ashape that generally conforms to that of the convex barrier side, suchthat the barrier and the breastshield side sidewall substantially matewhen in facial engagement (in the initial pre-load state or condition).

In the foregoing embodiment, the barrier becomes inverted under vacuum,and forms another generally convex shape when distended under vacuum, atleast in part, as presented by the now inside-out barrier side in thedistended state. A vacuum side sidewall has in this most preferred form,a shape that generally conforms to that of the distended barrier side,such that the barrier and the vacuum side sidewall substantially matewhen in facial engagement.

In another aspect of the present invention, the barrier has a pluralityof generally concentric undulations designed to provide bending momentsfor the barrier tending to return from a distended state to an initialstate. This is contrasted with stretching of a barrier of the prior art,rather than bending.

It is yet another advantage of the present invention to provide abreastpump assembly which isolates parts of the pump in a vacuum linefrom contamination, such as between a breastshield and a vacuum sourcein communication with the breastshield via the vacuum line. The vacuumline is in communication with a housing that has a breastshield side andvacuum side. A resilient barrier having a form with a first surface thatis, at least in part, generally domelike with an unassembled dome heightas measured from a base of the dome to the first surface. The resilientbarrier is assembled in the housing in a manner to separate and therebyisolate the breastshield housing side and vacuum housing side in aninitial state with a pre-loaded condition for the barrier. Thepre-loaded condition of the barrier has an assembled dome height that isless than the unassembled dome height.

Furthermore, the vacuum realized on the breastshield side follows agenerally one to one relationship with the vacuum applied on the vacuumside, after an initial level of vacuum is realized on the vacuum pumpside to overcome the pre-load condition. The initial level of vacuum toovercome the pre-load condition can be about 4 to 15 mmHg (negative) inone form of the invention. This yields a highly efficient vacuumtransfer across the barrier. The foregoing embodiment can furtherinclude a milk conduit structure which conveys milk from thebreastshield to a container via a catch chamber and a one-way valvebetween the catch chamber and the container. The barrier, upon returningto an initial state with a predetermined minimum amount of milk in thecatch chamber, generates an increased pressure in the catch chamberrelative to the container so as to open the valve and release milk totravel into the container.

These, together with other objects and advantages will be furtherunderstood in the details of the construction and operation of theinvention as more fully hereinafter described, reference being had tothe accompanying drawings, forming a part hereof, wherein like numeralsrefer to like parts throughout, in which:

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1A is a perspective view of a contamination barrier in a free stateaccording to the present invention;

FIG. 1B is a perspective view of the barrier of FIG. 1A from the otherside;

FIG. 2 is a side view of the contamination barrier of FIG. 1;

FIG. 3A is a front side perspective view of a breastpump assemblyaccording to the present invention;

FIG. 3B is the breastpump of FIG. 3A from the back side;

FIG. 4 is an exploded perspective view from the front side of thebreastpump assembly of FIGS. 3A and 3B according to the presentinvention (without the bottle);

FIG. 5 is an exploded perspective view from the back side of thebreastpump assembly of FIG. 4;

FIG. 6A is a side view of the contamination barrier of FIG. 2 in apre-loaded state according to the present invention;

FIG. 6B is a side view similar to that of FIG. 6A with the barrierdistended;

FIG. 7A is a side sectional view of the breastpump assembly of FIGS. 3Aand 3B;

FIG. 7B is a sectional view of the breastpump assembly of FIG. 7A.

FIG. 8 is an enlarged sectional view similar to that of FIG. 7B in onephase;

FIG. 9 is a sectional view similar to that of FIG. 8 in another phase;and

FIG. 10 is a comparison chart of performance (curves) of variousmembranes.

DETAILED DESCRIPTION OF AN EMBODIMENT OF THE INVENTION

Although the embodiments of the present invention described herein aredirected to breastpump assembly systems, which is the particularenvironment that the invention finds its origin, it is contemplated thatthe present invention has various other applications, such as any pumpsystem that requires a barrier to prevent contamination, or that maybenefit from a movable membrane that is very efficient in transmittingpressure changes from a volume (or working fluid) on one side to avolume (or working fluid) on the other side.

The barrier of the present invention works with simple manually operatedbreastpumps that may provide only suction (and a vent to atmosphere), aswell as more complex pumps, such as motorized pumps, and pumps providingboth suction and a positive pressure. Thus, while described inparticular respects with a source of vacuum, the pressure source couldalso be a positive pressure moving the barrier.

FIGS. 1A and 1B illustrate a self-returning contamination barrier 100 ina “free” state according to the present invention; that is, unassembled,and as it may be molded. The barrier includes an inner surface 102, andouter surface 104. As shown, the outer surface 104 includes threeconcentric circular panels 106, 108, 110, although any number of panelsand any concentric shape are contemplated. The panels 106, 108, 110 areamalgamated, or joined, via sidewalls 112. Sidewall 112 a joins centerpanel 106 to intermediate panel 108. Sidewall 112 b joins intermediatepanel 108 to exterior panel 110. Exterior panel 110 is amalgamated(joined) with a rim 114 via sidewall 112 c. As shown, and discussed inmore detail hereafter, a valve 101 formed integral with barrier 100, butit is contemplated that the valve 101 could be separate and apart fromthe barrier 100.

The self-returning contamination barrier 100 is made of a resilientmaterial, such as an elastomer, or any plastic and rubber combinationthat permits the barrier to function as a spring, described more fullybelow. The preferred embodiment is constructed of liquid injectionmolded silicone (LIMS), such as LIM 6050 that available from GeneralElectric (GE).

The barrier 100 is assembled with a breastpump protection to eliminatecontamination in the pump air line. FIGS. 3A and 3B illustrate abreastpump assembly 200. The assembly 200 includes a detachablebreastshield 202. The breastshield 202 engages with a breast to form aseal to ensure suction to the breast, while maintaining comfortability.The front housing 204, also referred to herein as first housing, frontside, or breastshield side, includes an interface or base part 205 andbottle collar 208. Breastshield 202 is detachably connected to theinterface 205 of front housing 204 (although it could be made integraltherewith). A collection container or bottle 210 is attached to thecollar 208 of the front housing 204. The rear housing 206, also referredto herein as second housing, back side, or vacuum side, includes a port212 to connect to an electrically operated pump, otherwise referred toas the vacuum source.

FIG. 4 and FIG. 5 illustrate an exploded view of the breastpump assembly200 according to the present invention. The rear housing 206 includes aninterior rearwall surface 402 and an exterior surface 404. The fronthousing 204 includes an interior frontwall surface 502, and an exteriorsurface 504. As assembled, the barrier 100 is positioned between theinterior rearwall surface 402 of the rear housing 206 and the interiorfrontwall surface 502 of the front housing 204.

The frontwall surface 502 most preferably has a shape that generallymatches the outer surface 104 of the barrier 100 when it is in facialengagement in the initial state. The interior rearwall surface 402 mostpreferably has a shape that generally matches the inner surface 102 ofthe barrier 100 in a distended (inverted) state, described more fullybelow. The rim 114 forms a seal between the interior surface 502 of thefront housing part 204 and the interior surface 402 of the rear housingpart 206.

Once assembled within the housing, the barrier 100 separates andisolates the breastshield side of the housing 204 and the vacuum side ofthe housing 206. The barrier 100 is assembled in a pre-loaded initialstate, also referred to herein as a first or initial position, or state,and maintains a concave shape as viewed from the vacuum side or a convexshape as viewed form the breastshield side, between the housing parts204, 206, as shown in FIG. 6A. In this first position, the barrier 100is biased toward the breastshield side of the housing 204.

As can be seen from FIG. 6A, the center panel 106 and sidewall 112 a aresubstantially aligned with intermediate panel 108 in the pre-loadedstate, i.e., when assembled. In addition, sidewalls 112 b, 112 c in acompressed configuration in the pre-loaded state, in comparison to thefree state (FIG. 2). Looking at this another way, the barrier 100 has adome-like shape, with a central axis. In the free state of FIG. 2, theheight of the dome, as taken along this axis from rim 114 to the frontsurface of the convex side (panel 106), is h₁. In the pre-load state ofFIG. 6A, the dome is compressed to a height of h₂, where h₂ is less thanh₁. The pre-loaded state assists in the functionality (spring action) ofthe barrier 100 during operation, described more fully below.

With reference to FIGS. 7A and 7B, the breastshield 202 connects to theinterface (collar or shield base) 205 of the front housing 204. Whenmilk is expressed from the breast of a nursing mother, the milk therebyflows from the breastshield 202 through a liquid conduit 702 portion toa collecting or catch chamber 704, and then to the collection container210 (here, a bottle). At the outlet of the collection chamber 704 thereis provided a valve 101 which closes the collection chamber 704, leadingto bottle 210. Valve 101 in this instance is shown integrated withbarrier 100, but again, it is contemplated that the valve 101 could beseparate and apart from the barrier 100. This system is not dependent onthis type of valve, in any event.

When a vacuum or negative pressure is applied to the breastshield 202from a well known type of suction device 706, which may be manuallyoperated or motor driven, the valve 101 closes the collection chamber704, and a negative pressure is applied to the interior of thebreastshield 202. Milk is collected within the collection chamber 704.When the negative pressure is released, the valve 101 opens to pass milkexpressed into the breastshield 202 and thence to the collection chamber704, to flow into the bottle 210. As noted, the valve mechanism may beof many types, for example a duckbill type.

The vacuum or suction device 706 here is a house-current driven vacuumpump using a tube, or air line 708 to convey the vacuum, although it iscontemplated that the vacuum device 706 may be a manually operatedpiston pump, or a battery operated diaphragm pump. The invention hereinis, however, not limited to any particular kind of vacuum device.

The vacuum source 706 connects via air line tube 708 to a port 212formed on the rear housing 206. The port 212 extends through surface 402and communicates with the interior of the rear housing 206. There is aninterior surface 502 of the front housing 204, against which the barrier100 is initially positioned, as shown in FIG. 7B. The breastshield sideof the housing 204 has an aperture 207 that extends into the conduitstructure communicating with interior space 209 within the connectingcollar 208. The vacuum in the rear housing 206 is thereby communicatedto the breastshield 202 by movement of the barrier away from the frontwall surface 502, which in turn draws air through aperture 207 fromspace 209 and within the breastshield 202. The above describes a vacuumconduit structure which conveys the vacuum from the source 706 to thebreastshield 202.

As stated, just before the vacuum source is applied, the barrier 100 isin facial engagement with the interior frontwall surface 502 of thefront housing 204. The frontwall surface 502 has a shape that generallymatches the outer surface 104 of the barrier 100 in this initial state.This matching engagement, which could also be less exact forsubstantially matching engagement, provides the smallest amount of“dead” volume on the breastshield side. It should be appreciated thatthe invention provides a very efficient vacuum transfer mechanism, whichwill use less energy and therefore extend the useful life of abattery-operated pump.

The breastpump assembly 200 of the present invention operates through abreastpump cycle of suction, air line release, and milk release. FIGS. 8and 9 illustrate the breastpump in the first phase, or suction phase.During operation, two pressures are realized on each side (breastshieldside and vacuum side) of the barrier 100: a first pressure A on thevacuum side of the barrier 100, otherwise referred to herein as pumpvacuum, and a second pressure B on the breastshield side of the barrier100, otherwise referred to herein as breastshield vacuum. The pump 706communicates a negative pressure to the barrier 100 via the air line 708such that the first pressure A is at least initially greater (morenegative) than the second pressure B, yielding what is known as adifferential vacuum. This differential vacuum ultimately causes thebarrier 100 to reach a distended state. The pump 706 draws a negativepressure (relative to atmosphere), which pulls the barrier 100 back intoa second position, or distended state (see FIG. 8). The now invertedbarrier 100 is in facial engagement with interior rearwall surface 402of the rear housing 206 in the full distended state. The rearwallsurface 402 has a shape that generally matches the inner surface 102 ofthe barrier 100 in this distended state.

As shown in FIG. 6B, when a vacuum is applied to the inner surface 102of the barrier 100, the barrier 100 essentially turns inside out, suchthat an initial convex shape (FIGS. 2 and 6A) is transformed to aninverted convex shape (FIG. 6B). The center panel 106′ is displaced fromintermediate panel 108′ via sidewall 112 a′, while the intermediatepanel 108′ is displaced from the exterior panel 110′ via 112 b′ and theexterior panel 110′ is displaced from the rim 114 via sidewall 112 c′.Sidewalls 112 a′, 112 b′, 112 c′ are substantially lengthened in thedistended state 900 in comparison to both the free state (FIG. 2) andthe initial state (FIG. 6A).

As the barrier transforms to and from a distended state and an initialstate, the exact position of barrier between the front housing 204 andrear housing 206 is determined by the difference between the firstpressure A on the vacuum side of the barrier and the second pressure Bon the breastshield side, i.e., differential vacuum. In addition to afirst pressure and second pressure, the barrier 100 defines a firstvolume on the vacuum side and a second volume on the breastshield side.It should be noted that as the barrier moves, the first volume andsecond volume (in addition to the first pressure and second pressure)change respectively.

In the collection chamber release phase, vacuum is released, typicallyby release to atmospheric pressure into the air line 708. The breastpumpenters the air line release phase where energy stored (pre-load) in thebarrier 100 causes the barrier 100 to return to its initial state (FIGS.6A and 9). The second pressure B returns to atmospheric level if no milkhas been added to the collection chamber 704. If no milk, or air fromleakage around the breast, has been added to the collection chamber 704,the valve 101 does not open and the breastpump cycle repeats until milkis collected in the collection chamber 704. If milk is present, however,the air volume in the breastshield side will have been reduced by themilk volume. The barrier 100 pre-load then creates an overpressure(relative to the container) within the collection chamber 704, openingthe valve 101. That is, as the barrier 100 transforms from the distendedstate, the differential vacuum reverses wherein the first pressure Adecreases and the second pressure B increases. With a pressure equal orgreater than atmospheric pressure within the collection chamber 704,milk in the pathway can flow through valve 101 from the collectionchamber 704 into the collection container 210, i.e., milk release phase.The barrier 100 utilizes its pre-load during displacement topneumatically apply a pressure to the milk thus opening the valve 101and releasing the milk into the collection container 210. As the milk isreleased, the pressure applied by the barrier 100 decreases to thepre-load represented by the initial state of the barrier. After the milkis released, the valve 101 closes. The vacuum system then repeats thephases again through this cycle, beginning with the suction phase.

It will be noted that the invention may be adapted so that the barrierdoes not return completely to the initial state. This might be in asituation where minimum vacuum level is to be maintained in thebreastshield during pumping. The tendency of the barrier nonethelesscauses it to move toward that initial state, if not achieving it.

FIG. 10 is a comparison chart of performance (curves) of variouscontamination barriers. As indicated in the graph of FIG. 10, pressuredrop across the barrier, or differential pressure, is indicated alongthe y-axis (in millimeters of mercury) and vacuum side suction (inmillimeters of mercury) is along the x-axis. The graph indicates valuesbased on one pumping cycle drawn up to −250 mmHg. The pressure drop isthe difference between the pressure on the breastshield side of thebarrier and the pressure on the pump side of the barrier.

The FREESTYLE curve was made with an embodiment of the invention. Asindicated, it had a pre-load of 4 mmHg, i.e., it required that amount ofvacuum before the barrier began to move. PURELY YOURS, ISIS IQ DUO andEMBRACE are commercial products. They are assembled without a pre-load.As can by seen in FIG. 10, FREESTYLE, which incorporates the advantagesof the present invention, had the most consistent pressure drop acrossthe barrier for the entire vacuum range. This illustrates an excellentmechanical transfer, and a reduced amount of energy required on thebreastpump system, when a barrier contemplated by the present inventionis implemented. The FREESTYLE barrier is most efficient in that theenergy loss is minimal once the pre-load is overcome.

It is understood that there may be many shapes, sizes, andconfigurations of the barrier that will fall within the scope of theinvention. The use of the terms dome, concave and convex does not limitthe invention to a round barrier. Any shape, e.g., non-round barrier iscontemplated with material thickness and shape varying with respect todistance and angle from the center of the barrier to achieve the springaction discussed herein. It is seen that the objects set forth above,among those made apparent from the preceding description, areefficiently attained and, since certain changes may be made in the aboveconstructions without departing from the spirit and scope of theinvention, it is intended that all matter contained in the abovedescription or shown in the accompanying drawings shall be interpretedas illustrative and not in a limiting sense. It is also to be understoodthat the following claims are intended to cover all of the generic aswell as specific features of the invention herein described, and allstatements of the scope of the invention that, as a matter of language,might be said to fall therebetween.

While the present invention has been described with reference to aparticular embodiment, those skilled in the art will recognize that manychanges may be made thereto without departing from the scope of thepresent invention. Each of these embodiments and variants thereof iscontemplated as falling with the scope of the claimed invention, as setforth in the following claims.

What is claimed is:
 1. A breastpump assembly, comprising: abreastshield; a conduit structure adapted to convey pressure and liquid;a collection container communicating with said conduit structure; ahousing; a vacuum source communicating with said housing; and aresilient barrier assembled in a pre-loaded initial state between partsof said housing, wherein said barrier achieves a distended state inresponse to vacuum from said vacuum source and said barrier utilizessaid pre-load to assist in transforming from said distended state tosaid initial state.
 2. A breastpump assembly, comprising: abreastshield, a vacuum source in communication with said breastshieldvia a vacuum line, a housing having a front side and a back side, saidhousing being adjacent to said breastshield; and a resilient barrierassembled in an initial pre-loaded state between said front side andsaid back side of said housing, wherein said barrier achieves adistended state in response to an applied vacuum from said vacuum sourceand said barrier returns from said distended state upon release of saidapplied vacuum.
 3. An improved breastpump assembly, wherein saidassembly has a contamination barrier located in a pressure line betweena pressure generating pump and a breastshield, wherein the improvementcomprises: a housing having a breastshield side and a pressure side; andsaid barrier separates and isolates said housing sides, said barrierhaving a shape and being assembled within said housing in an initialpre-loaded state between said housing sides such that said barrier has apre-set bias in a direction toward said breastshield side in the absenceof an applied pressure.
 4. The improved breastpump assembly of claim 3wherein said barrier has a distended state in response to an appliedvacuum from said vacuum source, and said barrier returns toward saidinitial state upon release of said applied vacuum.
 5. The improvedbreastpump assembly of claim 4 wherein said barrier has a generallyconvex shape at least in part presented by a convex barrier side, and isassembled within said housing so that said bias presses said convexbarrier side against an internal breastshield side sidewall of saidhousing in said initial state.
 6. The improved breastpump assembly ofclaim 5 wherein said convex barrier side further has at least oneundulation formed in its surface generally concentric with a center ofsaid convexity.
 7. The improved breastpump assembly of claim 6 whereinsaid internal breastshield side sidewall of said housing has a shapethat generally conforms to that of said convex barrier side, such thatsaid barrier and said breastshield side sidewall substantially mate whenin facial engagement.
 8. The improved breastpump assembly of claim 7wherein said barrier becomes inverted in said distended state.
 9. Theimproved breastpump assembly of claim 8 wherein said housing has avacuum side sidewall, wherein said vacuum side sidewall of said housinghas a shape that generally conforms to that of said inverted barrier,such that said barrier and said vacuum side sidewall substantially matewhen in facial engagement.
 10. The improved breastpump assembly of claim6 wherein said barrier has a plurality of generally concentricundulations designed to provide bending moments for said barrier tendingto return said barrier from said distended state to said initial state.11. A breastpump assembly comprising: a breastshield within which awoman's breast and nipple are received, a container for expressed milk,a source of vacuum, a mechanism modulating said source of vacuum, avacuum conduit structure which conveys a vacuum from said source to saidbreastshield, a resilient barrier in said vacuum conduit structurelocated in close proximity to said breastshield, said barrier beingmounted within a housing, said housing having a breastshield side and avacuum side, said barrier separating said housing sides, said barrierhaving an outer surface and an inner surface forming at least in part aconvex shape made to give said barrier a bias toward said convex shapewhen returning from a distended position to a rest position, saidhousing having a breastshield side internal sidewall that generallyconforms to said barrier convex shape on said outer surface of saidbarrier, said barrier being mounted in said housing in a manner wheresaid outer surface of said convex shape is closer to said breastshieldside internal sidewall of said housing than said rest position of saidbarrier would otherwise allow, such that said bias presses said barrieragainst said internal sidewall for an initial pre-load condition of saidbarrier.
 12. The breastpump of claim 11 wherein said barrier has atleast one undulation formed generally radially spaced from andconcentric about the center of said barrier, said breastshield sideinternal sidewall of said housing having a surface shape that generallymatches said barrier convex shape on said outer surface of said barriersuch that said barrier substantially mates with said breastshield sideinternal sidewall surface in facial engagement in said initial pre-loadcondition.
 13. The breastpump of claim 12 wherein said vacuum sideincludes a rearwall surface having a shape that generally matches saidbarrier shape in said distended position wherein said barrier has beenmoved by application of said vacuum from said source from said restposition and has become deformed in said distended position, such thatsaid deformed barrier substantially mates with said rearwall surface ofsaid vacuum side in facial engagement in said distended state.
 14. Abreastpump assembly which isolates parts of the pump in a vacuum linefrom contamination, comprising: a breastshield, a vacuum source incommunication with said breastshield via said vacuum line, a housinghaving a breastshield side and vacuum side, said housing being incommunication with said vacuum line; and a resilient barrier having aform with a first surface that is at least in part generally domelikeand having an unassembled dome height as measured from a base for saiddome to said first surface, said resilient barrier being assembled insaid housing in a manner to separate and thereby isolate said housingsides from one another and in an initial state with a pre-loadedcondition wherein said barrier has an assembled dome height that is lessthan said unassembled dome height.
 15. The breastpump assembly of claim14 wherein said barrier achieves a distended state in response to anapplied vacuum from said vacuum source and said barrier returns fromsaid distended state back to said initial state upon release of saidapplied vacuum.
 16. The breastpump assembly of claim 15 wherein saidfirst surface of said barrier abuts an internal sidewall of saidbreastshield side of said housing in said initial state.
 17. Thebreastpump assembly of claim 16 wherein said barrier has a secondsurface on an opposite side to said first surface, wherein said secondsurface of said barrier abuts an internal sidewall of said vacuum sideof said housing in said distended state.
 18. The breastpump assembly ofclaim 17 wherein said barrier has a generally convex shape and least oneundulation formed generally radially spaced from and concentric about acenter of said barrier, said breastshield side internal sidewall of saidhousing having a surface shape that generally matches the shape of saidbarrier first surface such that said barrier in said pre-loadedcondition substantially mates with said breastshield side internalsidewall surface in facial engagement, said vacuum side internalsidewall of said housing having a surface shape that generally matchesthe shape of said barrier in said distended state wherein said barrierhas become inverted through movement from said initial state to saiddistended state, such that said inverted barrier substantially mateswith said vacuum side internal sidewall surface in facial engagement insaid distended state.
 19. The breastpump assembly of claim 14 whereinsaid barrier is made of a resilient material which in combination withsaid barrier shape causes said barrier to return from said distendedstate to said initial state on its own upon the release of said vacuum.20. The breastpump assembly of claim 14 wherein the vacuum realized onsaid breastshield side follows a generally one to one relationship withthe vacuum applied on said vacuum side after an initial level of vacuumis realized on said vacuum side to overcome said pre-load condition. 21.The breastpump assembly of claim 21 wherein said initial level of vacuumto overcome said pre-load condition is about 4 mmHg.
 22. The breastpumpassembly of claim 22, further including a milk conduit structure whichconveys milk from a breastshield to a container via a catch chamber anda one-way valve between said catch chamber and said container, saidbarrier upon returning to said initial state with a predeterminedminimum amount of milk in said catch chamber generates an increasedpressure in said catch chamber relative to said container so as to opensaid valve and release milk to travel into said container.
 23. Thebreastpump assembly of claim 14 wherein said barrier has a formed shapeof convexity in a demounted condition, and when mounted within saidhousing said barrier cannot reach said formed shape of convexity in saidinitial state, such that said barrier is pressed against said housingfrontwall in said initial state.